11. Wine Components Flashcards
How much water is in wine?
Wine is approximately 85% water by volume depending on the abv, level of residual sugar and other factors.
What is the predominant alcohol in wine?
Ethanol
What does alcohol contribute to the final wine?
- Ethanol contributes a sense of sweetness and bitterness, and oral warmth.
- It also makes a contribution to the fullness of the body of a wine and the mouthfeel.
- Alcohol levels of 14.5% and above reduce the volatility of wine aromas and increase the sense of bitterness.
What are the principle acids in wine?
Malic and tartaric
Both come from the grape itself
Name two examples of minor acids in wine and how do they occur?
Lactic acid and acetic acid
Produced in fermentation or malolactic conversion. (Rather than coming from the grape itself).
What is volatile acidity?
Volatile acidity mainly refers to acetic acid (vinegar smell), although some other compounds can contribute.
It is present in all wines, generally in low concentrations, and is only a fault when in excess. Acetic acid in turn reacts with the alcohol in the wine and becomes ethyl acetate (nail varnish remover smell), which is also perceived as a fault when in excess.
How does acidity influence the final structure of the wine?
Acidity contributes to the structure of wine, makes wine refreshing and should be in balance with the fruit concentration and, if present, residual sugar, depending on the style of the wine. High acid also makes wine appear leaner on the palate. Excessive acid will make wine taste tart. Lack of acid will make wine taste flabby.
How is acidity in wine usually measured?
The most common measure is ‘total acidity’, which is the sum of all the acids. Although there are many acids present, the result will usually be expressed as the equivalent of grams per litre (g/L) in tartaric acid. Total acidity in wine is typically in the range of 5.5–8.5 g/L.
How does a low PH level influence the final wine?
A low pH increases the microbiological stability of wine, increases the effectiveness of SO2, gives red wines a bright red colour and enhances a wine’s ability to age well.
What are the typical PH levels in most wines?
(higher acidity) **3-4 **(lower acidity)
Give two well-known examples of aroma compounds already found in grapes.
- Methoxypyrazines occur in the Sauvignon Blanc variety and give a grassy, green pepper aroma.
- Rotundone occurs in Syrah and in Grüner Veltliner, producing a pepper aroma.
What are aroma precursers?
Aroma precursors are compounds that are not in themselves aromatic but are building blocks which become aromatic during fermentation.
What are terpenes? Example?
Terpenes are a category of aroma precursers that are released during fermentation.
4MMP which gives the box tree aromas in Sauvignon Blanc.
What are thiols? Examples?
Thiols are a category of aroma precursers that are released during fermentation.
Examples such as linalool and geraniol contribute to the grapey aromas/flavours in Muscat.
What are esters and how are they formed?
Esters are compounds which are formed by the reaction of certain acids and alcohols. The majority are created through the action of yeasts in the fermentation process.
Most esters are unstable and will break down a few months after fermentation.
